For many years, wire nails have been used in countless numbers for wood-fastening and other applications. Pneumatically powered nailing tools and, in recent years, combustion-powered nailing tools have been used extensively to drive such nails.
Typically, wire nails are made from steel wire with a shank defining an axis, a head formed on one end of the shank, and a point formed on the other end of the shank. Although various points have been known, a standard point has evolved, which is characterized by four flat, triangular facets, each lying in a plane oriented at an angle of about 20.degree. relative to an axis defined by the shank. Such a point tends to be quite sharp.
Many efforts have been made to increase the resistance of such nails to withdrawal. Such efforts have been focused primarily on their shanks, which consequently have been coated, etched, spirally grooved, annularly grooved, or barbed, so as to increase their resistance to withdrawal. Diverse coating agents have been used to increase such resistance, e.g., poly(vinyl acetate). Blunt-pointed mails have been used to minimize splitting of wood.
Although wire nails as known heretofore have proved to be generally satisfactory for many applications, their utility would be greatly enhanced if their resistance to withdrawal could be further increased.